Method of shredding rubber



May 11, 1943. w. .1. JOYCE ET AL METHOD OF SHREDDING RUBBER Filed Nov. 29, 1939 E O \HIHIIIH LNVENTORS Ill/ILLIHM J Java JR.

, HQRVEYE GEYL'R 5, ATTORNEYS Patented May 11, 1943 UNITED STATES PATENT OFFICE 2,318,693 x I METHOD OF SHREDDING RUBBER. William-J. Joyce and Harvey D. Geyer, Dayton,

Ohio, assignors to General Motors Corporation, Detroit, Mich;, acorporation of Delaware Application November 29, 1939, Serial No. 306,636

2 Claims.

This inventionrelates to a process of shredding or exploding rubber-like material.

An object of the invention is to provide a 7 method for shredding rubber-like material wherein a fluid is dissolved into the material .under suitable high pressures and then by instantaneous reduction of the-pressure the spin-- bility of the fluid is reduced forcausin'g' the rubber-like material to explode and thereby be shredded. I I

In carrying out the above object a further object of the invention is to use a compressible fluid that has no deleterious efiects on the rubber-like material and which has thermo-dynamic properties which permit the desired action at sufliciently low temperatures to prevent iniury to the rubber-like material. It is a still further object to use such soluble compressible fluids as ammonia, sulphurdioxide, methyl chloride etc. I v

Further objects and advantages of the'pres ent invention will be apparent from the following description, reference being had to the accompanying drawing wherein preferred embodiment of the present invention is clearly shown. In the drawing the figure shows a schematic layout oi the explosion apparatus.

Rubber like material as herein noted, which defines rubber, crude, compounded, either .vulcanized or unvulcanized, reclaimed rubber, synthetic rubbers such as polymerized chloroprene, polymerized isoprene and the like has a solvent action upon certain fluids, such fluids including, ammonia, methyl chloride, sulphur dioxide, hydrogen sulphide, nitrous oxide, propane, ethane,

ethylene etc., or suitable mixtures thereof. When.

within the rubber thereby causing a shredding action on the rubber.

When choosing a compressible fluid, for the herein described purpose, care should be exercised to choose a fluid which has no deleterious ei'iects on the material, that is, av fluid'should be chosen which has the proper thermodynamic properties to permit solution without undesirable chemical action and without an increase in tem perature sufllcient to injure the rubber-like material. w

We are aware of the Mason Patent 1,578,609, wherein steam is used in connection with porous pores of the wood at an elevated pressure and upon' a release of the pressure the steam: which is in a compressed condition is releasedtoxcause the wood to'become comminuted. Our process is entirely different, since we propose tooperate upon rum-porous material such as rubber, and

iwfefurther propose to use a fluidwhich is sol- ,uble in rubberand which, in addition, will permit the desired action at suificie'ntly low te'm peraturesftoprevent injury to. the-material.

In order-to more clearly define our inventionv theiollowing speciflcexample is given inillus- -trative purposes only. Unvulcanized rubber,

means such'aa'element 24, to a high pressure approximating 1500 lbs. per sq. inch. The vapor is their admitted to thechamberjzll' containing the -rubber-by- .o'p'erationoi'. valve 25 whereupon "therapis -isdissolved into the rubber.

chamber 'Iljcontaining the rubber, is: provided with a sma'ill orifice outlet 28 whichjs controlled by a suitable'valvemechanism 30 and after a predetermined time has elapsed to permit the desired solution of the vapor in the rubber, the valve 30 is opened and the rubber containing the dissolved vapor is blown throu'gh-th'e orifice 28 into a chamber 32 which is preferably main.- tained' at substantially atmospheric pressure.

It is apparent,- that as the rubber passes: through the oriflcelat' high velocity, that the pressure 'drop approximates 1500 lbs. per sq. inch whereupon the solubility of the ammonia vapor is greatly reduced in the rubber, giving rise to exaccorded other types of rubber herein disclosed material, in this instance the steam enters the pansion and/or explosion of the rubber to permit the release of the vapor. .In this manner the rubber is broken up and shredded.

Itis manifest that similar treatments can be and that other solutes may be used, the only requirement being that the fluid which is to be dissolved into the rubber has such propertiesa to permit solution at temperatures which are not injurious to rubber-like material. Obviously, when using various solutes the pressures etc., may be varied to suit the particular case,-'such pressures being best arrived at by trial in connection with the solute and solvent to be used. The type and condition of rubber used in the process,the condition desired in the rubber after explosion, the ease of handling the gas. and cost are some of the factors influencing the selection of a. particular gas. For example, we find that The ammonia is very successful when it is desired to explode rubber but not permanently alter its chemical composition in the e plosion process. We have used sulphur dioxide w en we wished to explode rubber and at the same time cause oxidation in it. We have used methyl chloride to explode rubber prior to using the rubber in making rubber cement.

The product of thisinvention may be used in a number 01' ways for example, the shredded unvulcanized rubber can be baled and then molded" into definite shapes and used as a substitute tor sponge'rubber, one of such uses being particularly directed to seat cushions "of automobilesif Likewise, the process may be directed tocrude; rubber, wherein the exploded rubber is fed'directly to the mill where compoundingis taking place thusreducing the milling time. Vulcanized rubpolymerized chloroprene and polymerized isoprene comprising th steps'or, dissolving ammonia in rubber-like material under high pressure,

ber, such as, old tires, can be exploded by this method to present particles of verythin crosssection which may be easily operated upon. Thus it is apparent that the invention has a multitude of uses inaconnection withnonporous rubberlike material and thatalthough a diagrammatic showing is presented, such showing does not limitthe invention, since any suitable apparatus that v will produce the desired efiect, is within the scope,

of our invention.

As herein defined. the words rubber-like material as noted in the claimswill include rubber, crude, compounded, vulcanized or unvulcanized, reclaimed rubber, synthetic rubber such as polymerized chloroprene, polymerized isoprene and the like, such materials being or a non-porous nature as differentiated from wood and other porous materials.

a and then substantially instantaneously reducing the pressure andthereby reducing the solubility of the amnionia'in the rubber-like material for .causingthe ammonia to be released irom the rubber under explosive conditions, for breaking up the' rubber-like material into small particles.

2. The process of making shredded material from rubber-like material taken from the class consistingof crude rubber, compounded rubber, vulcanized rubber, unvulcanized rubber, re-

claimed rubber, polymerized chloroprene .and'

polymerized isoprene, comprising the steps of, in-

troducing rubber-like material into a chamber,. dissolving ammonia into said rubber-like mate:

rial, under high pressureand then ejecting .said

. rubber-like material with the ammonia dissolved therein into a zone of reduced pressure, whereby the solubility of the ammoniais reduced, for callsing the ammonia to be released with explosive forceand thereby shred the rubber-like material;

, J. JOYCE. HARVEY D, GEYER. 

